U.S. patent application number 12/511504 was filed with the patent office on 2011-02-03 for ultrasound-based tracheal tube placement device and method.
This patent application is currently assigned to Neltcor Puritan Bennett LLC. Invention is credited to Youzhi Li, Andy Lin.
Application Number | 20110023889 12/511504 |
Document ID | / |
Family ID | 43525823 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110023889 |
Kind Code |
A1 |
Lin; Andy ; et al. |
February 3, 2011 |
ULTRASOUND-BASED TRACHEAL TUBE PLACEMENT DEVICE AND METHOD
Abstract
An inflatable balloon cuff may be adapted to seal a patient's
trachea when associated with an endotracheal tube. These cuffs may
include features that facilitate detection or visualization of the
cuff, for example with ultrasound devices, to ensure proper
placement of the cuff and the tube. Such surface features may
include particular types of materials or shaped or protruding
features that may be detected in the environment of the
trachea.
Inventors: |
Lin; Andy; (Boulder, CO)
; Li; Youzhi; (Longmont, CO) |
Correspondence
Address: |
NELLCOR PURITAN BENNETT LLC;ATTN: IP LEGAL
6135 Gunbarrel Avenue
Boulder
CO
80301
US
|
Assignee: |
Neltcor Puritan Bennett LLC
Boulder
CO
|
Family ID: |
43525823 |
Appl. No.: |
12/511504 |
Filed: |
July 29, 2009 |
Current U.S.
Class: |
128/207.15 |
Current CPC
Class: |
A61M 16/0434 20130101;
A61M 16/0488 20130101; A61B 8/4483 20130101; A61B 8/4472 20130101;
A61M 16/0057 20130101; A61M 16/04 20130101; A61M 16/0443 20140204;
A61B 8/0833 20130101; A61B 8/0841 20130101; A61M 16/0459 20140204;
A61M 2205/502 20130101 |
Class at
Publication: |
128/207.15 |
International
Class: |
A61M 16/04 20060101
A61M016/04 |
Claims
1. A tracheal tube comprising: a conduit; and a balloon cuff
associated with the conduit, wherein the balloon cuff comprises an
inflatable region and wherein a portion of a balloon wall of the
inflatable region capable of contacting a trachea when inflated
comprises a surface feature capable of being detected by an
ultrasound transducer located outside a patient's body.
2. The tracheal tube of claim 1, wherein the balloon cuff comprises
polyethylene teraphthalate (PETP), low-density polyethylene (LDPE),
polyvinyl chloride (PVC), silicone, neoprene, polyisoprene,
polypropylene, or polyurethane (PU).
3. The tracheal tube of claim 1, wherein the tracheal tube is
operatively connected to a ventilator.
4. The tracheal tube of claim 1, wherein the surface feature
comprises an anti-reflective material disposed on the balloon
wall.
5. The tracheal tube of claim 4, wherein the anti-reflective
material comprises an interference coating.
6. The tracheal tube of claim 4, wherein the anti-reflective
material comprises a metal.
7. The tracheal tube of claim 4, wherein the anti-reflective
material comprises a nanofilm.
8. The tracheal tube of claim 4, wherein the anti-reflective
material comprises a refractive index within 20% of a square root
of a refiactive index of the balloon wall.
9. The tracheal tube of claim 1, wherein the surface feature is
disposed on a portion of the inflatable region capable of touching
a portion of the trachea adjacent to a sternal notch of the
patient.
10. The tracheal tube of claim 1, wherein the surface feature is
disposed on a portion of the inflatable region that does not touch
a portion of the trachea adjacent to a sternal notch of the
patient.
11. The tracheal tube of claim 1, wherein the surface feature
comprises a protruding or shaped feature.
12. The tracheal tube of claim 11, wherein the protruding or shaped
feature is formed in a portion of the wall of the balloon cuff.
13. The tracheal tube of claim 12, wherein the protruding or shaped
feature is at least approximately three times thicker than adjacent
portions of the balloon wall.
14. The tracheal tube of claim 1, wherein the conduit comprises an
alignment index to align the surface feature to a portion of the
conduit adapted to be facing a patient's ventral side when
inserted.
15. An inflatable balloon cuff for use in conjunction with a
medical device comprising: a proximal collar in a wall of the
balloon cuff capable of being attached to the medical device; a
distal collar in the wall of the balloon cuff capable of being
attached to the medical device; and an inflatable region between
the proximal collar and the distal collar, wherein the inflatable
region comprises an anti-reflective material.
16. The inflatable balloon cuff of claim 15, wherein the
anti-reflective material comprises an interference coating.
17. The inflatable balloon cuff of claim 15, wherein the
anti-reflective material comprises a metal.
18. The inflatable balloon cuff of claim 15, wherein the
anti-reflective material comprises a nanofilm.
19. A medical device comprising: a conduit; a first balloon cuff
associated with the conduit; and a second balloon cuff associated
with the conduit, wherein the second balloon cuff comprises an
inflatable region and wherein a portion of a balloon wall of the
inflatable region capable of contacting a trachea when inflated
comprises a surface feature capable of being detected by an
ultrasound transducer located outside a patient's body.
20. The medical device of claim 19, wherein the first balloon cuff
is adapted to seal the trachea and the second balloon cuff is
adapted to contact the trachea adjacent to a sternal notch of the
patient.
Description
BACKGROUND
[0001] The present disclosure relates to medical devices, and more
particularly, to airway products, such as tracheal tubes and
cuffs.
[0002] This section is intended to introduce the reader to various
aspects of art that may be related to various aspects of the
present disclosure, which are described and/or claimed below. This
discussion is believed to be helpful in providing the reader with
background information to facilitate a better understanding of the
various aspects of the present disclosure. Accordingly, it should
be understood that these statements are to be read in this light,
and not as admissions of prior art.
[0003] In the course of treating a patient, a tube or other medical
device may be used to control the flow of air, food, fluids, or
other substances into the patient. For example, tracheal tubes may
be used to control the flow of air or other gases through a
patient's trachea. Such tracheal tubes may include endotracheal
(ET) tubes, tracheotomy tubes, or transtracheal tubes. In many
instances, it is desirable to provide a seal between the outside of
the tube or device and the interior of the passage in which the
tube or device is inserted. In this way, substances can only flow
through the passage via the tube or other medical device, allowing
a medical practitioner to maintain control over the type and amount
of substances flowing into and out of the patient.
[0004] For example, a patient may be intubated by insertion of an
endotracheal tube through the patient's mouth and into the trachea.
Often, such intubation procedures may be performed during medical
emergencies or during critical care situations. As such, healthcare
providers may balance a desire for speed of intubation with a
desire for accurate placement of the tube within the trachea.
However, proper placement of a tracheal tube may be complex.
[0005] In certain situations, placement may be aided with
visualization of the trachea performed during laryngoscopy. During
an intubation procedure, a practitioner may employ a lighted
laryngoscope during introduction of the endotracheal tube. However,
often the visualization of the trachea is poor because of patient
secretions that may obscure the laryngoscope. In addition, such
visualization during introduction of the tube may not account for
ongoing changes in the tube's position within the trachea that may
occur when a patient coughs, which may dislodge a tube from its
desired location, or when a patient moves or is jostled within a
care setting, which may change the position or angle of the tube
within the trachea.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Advantages of the disclosure may become apparent upon
reading the following detailed description and upon reference to
the drawings in which:
[0007] FIG. 1 illustrates an exemplary system including an
endotracheal tube with a first pressure transducer and a second
pressure transducer according to certain embodiments;
[0008] FIG. 2 is a perspective partial cutaway view of an
endotracheal tube that may be used in conjunction with the system
of FIG. 1 according to certain embodiments;
[0009] FIG. 3 is a side view of a tracheal tube inserted into a
patient according to certain embodiments;
[0010] FIG. 4 is a top view of a tracheal tube inserted into a
patient according to certain embodiments;
[0011] FIG. 5 is a side view of a tracheal tube cuff including an
anti-reflective surface coating according to certain
embodiments;
[0012] FIG. 6 is a side view of a tracheal tube cuff including a
thick area in the balloon walls in a section of the cuff according
to certain embodiments;
[0013] FIG. 7 is a side view of a tracheal tube cuff including a
ridged or striped shaped area formed in the balloon walls according
to certain embodiments; and
[0014] FIG. 8 is a side view of a tracheal tube inserted into a
patient including a primary cuff and a secondary sealing cuff
according to certain embodiments.
DETAILED DESCRIPTION
[0015] One or more specific embodiments of the present disclosure
will be described below. In an effort to provide a concise
description of these embodiments, not all features of an actual
implementation are described in the specification. It should be
appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0016] A tracheal tube may be used to seal a patient's airway and
provide positive pressure to the lungs when properly inserted into
a patient's trachea. Positioning the tracheal tube at a desired
position within the trachea, for example during endotracheal
intubation, may improve the performance of the tracheal tube and
reduce clinical complications. In particular, the distal inserted
end of the endotracheal tube may be positioned in the patient's
trachea at a location substantially between the patient's vocal
cords and carina. If the tube cuff is not inserted far enough past
the vocal cords, for example, the tube may become more easily
dislodged. If the tube is inserted too far into the trachea, such
as past the carina, then the tube may only function to adequately
ventilate one of the lungs, rather than both. Thus, proper
placement of the distal tip of the tube generally results in
improved ventilation to the patient.
[0017] Described herein are tracheal tubes and systems for
facilitating proper placement of the tracheal tube relative to
certain anatomical structures in and around the patient's airway
and trachea. A healthcare provider may then use the information
about the location of the tracheal tube relative to the anatomical
structures (e.g., a patient's sternal notch) to determine whether
the tube is properly placed or whether the position of the tube
should be adjusted.
[0018] While ultrasound detection may be used to detect placement
of endotracheal tubes within the trachea, the impedance mismatch
between the tissue of the tracheal walls and the airspace in the
trachea results in reflection of most of the signal back to the
transducer and, thus, a low signal to noise ratio. In addition, the
signal is weakened by the presence of muscle tissue and bone that
prevent penetration of the signal into the trachea. Provided herein
are tracheal tubes with balloon cuffs that include features to
enhance ultrasound detection of the cuffs, for example by
ultrasound transducers held against the patient's skin. The
features allow the cuffs to be distinguished from the surrounding
airspace of the trachea and the tracheal walls. Because balloon
cuffs are inflated to touch the tracheal walls, ultrasound
detection of the cuffs themselves, rather than the tube, prevents
loss of signal to the surrounding airspace in the trachea, i.e.,
the ultrasound signal may pass from the tracheal tissue directly to
the cuffs rather than being lost to the air. Accordingly, balloon
cuffs with impedance that more closely matches the tissue of the
trachea may be more easily detected without the reflectance loss
that accompanies relatively large impedance mismatches between
materials. From the position of the cuff, clinicians may determine
information about the position of the tube itself, such as the
location of the distal end of the tube. In addition, if the balloon
cuffs as provided are probed by positioning the ultrasound
transducer at a location such as the patient's sternal notch,
(sometimes referred to as a suprasternal notch or jugular notch)
which provides a signal path into the trachea relatively free of
interfering anatomical structures, the resultant signal to noise
ratio may be improved.
[0019] The disclosed tracheal tubes, systems, and methods may be
used in conjunction with any appropriate medical device, including
without limitation a feeding tube, an endotracheal tube, a
tracheotomy tube, a circuit, an airway accessory, a connector, an
adapter, a filter, a humidifier, a nebulizer, nasal cannula, or a
supraglottic maskitube. The present techniques may also be used to
monitor any patient benefiting from mechanical ventilation, e.g.,
positive pressure ventilation. Further, the devices and techniques
provided herein may be used to monitor a human patient, such as a
trauma victim, an intubated patient, a patient with a tracheotomy,
an anesthetized patient, a cardiac arrest victim, a patient
suffering from airway obstruction, or a patient suffering from
respiratory failure.
[0020] FIG. 1 shows an exemplary tracheal tube system 10 that has
been inserted into the trachea of a patient. The system 10 includes
a tracheal tube 12, shown here as an endotracheal tube, with an
inflatable balloon cuff 14 including ultrasound detection features
as provided that may be inflated to form a seal against the
tracheal walls 16. In addition, the system 10 may include an
ultrasound transmitter/receiver (e.g., a transducer) 26 to transmit
signals into the trachea and receive the returned signals, which
may be then communicated to a monitor 30 for further analysis.
[0021] The system 10 may also include devices that facilitate
positive pressure ventilation of a patient, such as the ventilator
22, which may include any ventilator, such as those available from
Nelleor Puritan Bennett LLC. As noted, the system 10 may also
include monitor 30, which may be configured to implement
embodiments of the present disclosure to determine information
about the location of the tube 12 based upon the ultrasound signals
transmitted into and then received from the cuff 14. In addition,
the monitor 30 may be configured to calculate certain placement
parameters of the tube 12 based on the position of the cuff
relative to the placement of the ultrasound transducer 26. It
should be understood that the monitor 30 may be a stand-alone
device or may, in certain embodiments, be integrated into a single
device with, for example, the ventilator 22.
[0022] The monitor 30 may include processing circuitry, such as a
microprocessor 34 coupled to an internal bus 36 and a display 38.
In one embodiment, the monitor 30 may be configured to communicate
with the receiver 26, either through a cable connection or
wirelessly. The transducer 26 may also provide calibration
information to the monitor 30. Calibration information may be
stored on a barcode or a separate memory circuit, such as a memory
circuit or connector 42 associated with the tube 12. The
information may then be stored in mass storage device 40, such as
RAM, PROM, optical storage devices, flash memory devices, hardware
storage devices, magnetic storage devices, or any suitable
computer-readable storage medium. The information may be accessed
and operated upon according to stored instructions for the
microprocessor 34. The monitor 30 may be configured to provide
indications of the placement parameters, such as an audio, visual
or other indication.
[0023] FIG. 2 is a perspective partial cutaway view of an example
of a cuffed endotracheal tube 12 that may be used in conjunction
with the system 10. The balloon cuff 14 is disposed on a conduit 46
that is suitably sized and shaped to be inserted into a patient and
allow the passage of air through the airway path of the
endotracheal tube 12. Typically, the cuff is disposed, adhesively
or otherwise, towards the distal end 48 of the endotracheal tube
12. The balloon cuff 14 may, for example, be inflated and deflated
via a lumen 50 in communication with the balloon cuff 14, typically
through a hole or notch 52 in the endotracheal tube 12. The balloon
cuff 14 includes a proximal collar region 54 and a distal collar
region 56 formed in the cuff walls 55 and sized to accommodate the
conduit 46 and used to mount the cuff 14 to the conduit 46. The
collar regions 54 and 56 flank an inflatable region 58, which is in
fluid communication with lumen 50.
[0024] The endotracheal tube 12 may be configured to be inserted
directionally into a patient's trachea. Not only is tube 12
configured to be inserted distal end 48 first, but the tube 12 may
include a curve from the proximal end 60 to the distal end 48 that
is designed to follow the contours of a typical patient's airway.
Although this curve may be partially straightened out during
insertion, the tube 12 will retain at least some of the curvature
once inserted. Proper insertion of the tube 12 will typically
result in the inside face of the curve 62 facing the patient's
ventral, i.e., front, side. As shown in FIG. 3, curve 62 faces the
sternal notch 65, which may be a location against which the
ultrasound transducer 26 may be placed, the ultrasound-detectable
features on the cuff 14 may be adapted to be aligned to correspond
with the inside curve 62, e.g., to be located in region 64 of the
cuff 14. When the cuff 14 is inflated, region 64 corresponds with
the area of cuff that is closest to the patient's sternal notch
65.
[0025] Turning back to FIG. 2, in certain embodiments, the
ultrasound-detectable features may be distributed all along or
within the walls 55 of the cuff 14. However, in other embodiments,
the ultrasound-detectable features may be distributed only within
region 64 and not in other regions of the cuff 14. To ensure that
these features are located as closely as possible to the
measurement site outside the body when the tube 12 is in place, the
tube 12 may include alignment features to allow any
asymmetrically-distributed features of cuff 14 for ultrasound
detection to be positioned correctly relative to the conduit 46. To
ensure that region 64 is aligned with the inside curve 62 of the
tube 12, the inside curve 62 may include one or more alignment
indicators 66, which may be indicators of any type, including text,
image, ink, chemical, or raised or shaped topographic markers,
disposed on the inside curve 62 of the tube 12. The alignment
indicators may be used to align the ultrasound-detectable features
to the inside curve 62. In other embodiments, where the ultrasound
transducer 26 is placed, for example, dorsally on the body, the
alignment indicators 66 may be located on the tube 12 to align the
ultrasound-detectable features to a location that will allow the
features to contact the trachea on its dorsal side. Further, the
cuff 14 may include additional alignment indicators. For example
such alignment indicators may be useful in embodiments in which the
ultrasound-detectable features are not visible to the naked eye or
are otherwise difficult to align.
[0026] As noted, the ultrasound-detectable features may be
distributed asymmetrically on the cuff 14. For example, they may be
distributed on only a section of the cuff 14. FIG. 4 is a top down
view of cuff 14 inflated against the tracheal walls 16. As noted,
the ultrasound-detectable features may be distributed within and/or
limited to a particular region, such as region 64, on the cuff 14.
In other embodiments, the ultrasound-detectable features may be
disposed along a circumferential section of the cuff 14 as viewed
through a cross-section of the tube 12. The distribution of the
ultrasound-detectable features may be, in embodiments, equal to or
less than a 180.degree. section, a 90.degree. section, or a
60.degree. section.
[0027] In particular embodiments, the ultrasound-detectable
features in the cuff 14 may be incorporated within the cuff walls
55 or may be provided as a coating 74 on the cuff walls 55, either
on the exterior patient side, as shown in FIG. 5, and/or as an
interior coating (i.e., inside the inflatable region 58 of the
cuff. For example, appropriate ultrasound-detectable features may
include metals or other materials that more closely match the
impedance of the cuff. In certain embodiments, the materials may be
anti-reflective materials that are configured to reduce reflection
of an ultrasound signal. Anti-reflective materials may include
interference coatings (such as MgF2), silica coatings, titanium
nitride, niobium nitride, or nanostructured coatings.
Nanostructured coatings may include repeating nano bumps or
protrusions that are smaller than the wavelength of light or sound
used. In one embodiment, the anti-reflective materials may be
configured to match the impedance of the balloon walls, e.g., the
anti-reflective materials may have a refractive index within 20% of
a square root of a refractive index of the balloon wall.
[0028] In other embodiments, the ultrasound-detectable features may
be formed of balloon wall material and may be thicker regions of
the balloon wall 55. As shown in FIG. 6, a balloon wall may form a
thick area 78 within region 64. For example, the balloon walls may
be several millimeters in thickness within all or part of region
64, while the balloon walls 55 in the inflatable region 58 (but
outside of region 64) may range in thickness from 0.015 mm.+-.0.007
mm to about 1 mm in thickness. In an alternative embodiment, the
ultrasound-detectable features may be shaped or patterned. FIG. 7
shows a cuff 14 with multiple ridges or stripes 80 formed from the
balloon walls 55. As shown, the stripes 80 may be located at least
in part within a particular portion of the cuff 14, such as within
region 64.
[0029] Often, clinicians may insert the tube 12 so that the cuff 14
is positioned at the sternal notch. However, depending on a
patient's particular anatomy, the clinician may prefer to insert a
sealing cuff just below the sternal notch. Because the sternal
notch provides certain advantages for the placement of the
ultrasound transducer 26, in such embodiments, the cuff 14 may be
arranged to line up with the sternal notch while a second sealing
cuff 82, as shown in FIG. 8, may be arranged on the tube 12 to be
positioned correctly below the sternal notch. The cuff 14 may be
primarily used for ultrasound detection and determination of the
tube placement while the sealing cuff 82 may be used to seal the
tracheal space. The cuff 14 may be only intermittently inflated,
for example during initial placement determination or during any
spot checking of tube placement.
[0030] The medical cuff 14 may be formed from materials having
suitable mechanical properties (such as puncture resistance, pin
hole resistance, tensile strength), chemical properties (such as
forming a suitable bond to the conduit 46), and biocompatibility.
In one embodiment, the walls of the inflatable cuff 14 are made of
a polyurethane having suitable mechanical and chemical properties.
An example of a suitable polyurethane is Dow Pellethane.RTM.
2363-90A. In another embodiment, the walls of the inflatable cuff
14 are made of a suitable polyvinyl chloride (PVC). Other suitable
materials include polypropylene, polyethylene teraphthalate (PETP),
low-density polyethylene (LDPE), silicone, neoprene, polyisoprene,
or polyurethane (PU).
[0031] The cuffs 14 may be manufactured by any suitable process,
such as by blow molding. In one example, a tube, such as an
extruded polyurethane tube, is loaded into a blowing machine or
mold assembly, such as a cross-section of a mold assembly that
includes shapes in the mold corresponding to the desired shape of
the detection features, e.g., thicker walls, ridges, or other
shaped features. In addition, the mold may include alignment
indicators, e.g., protrusions, depressions to line the detection
features with a particular curve of the tube 12. In one embodiment,
the mold assembly is manufactured from beryllium copper and
includes a horizontal split in the assembly to allow opening and
closing of the mold assembly. In an embodiment, the mold assembly
may include mating symmetrical pieces that close together. The mold
assembly may include integrated guide pins to prevent misalignment
of the two mold halves. In one embodiment, the end-portions of an
extruded tube that project out from the mold are constrained to the
shape and thickness of the original extruded tube by non-heat
transferable plastic holders at the ends of the mold. In one
embodiment, the blow molders are model 2219H-LP blow molding
machines, available from Interface Associates, that are configured
to run at 1-2 bars of gas pressure.
[0032] Once loaded, the mold assembly is closed, and the tube is
clamped at each end. The mold may then be heated. The tube may be
stretched and air is blown into the tube via an air conduit, such
as an air hose or nozzle, connected to a source of pressurized air,
such as an air pump or pre-pressurized source, to achieve a desired
positive pressure within the tube and to blow out the cuff walls to
the shape of the mold assembly. Additional heat may be applied to
the tube, such as via heating elements integral to the mold
assembly to set the shape of the cuff 14. As the heat is applied,
the stretch of the tube is relaxed and the air pressure within the
tube is increased. Once the desired temperature is reached it is
maintained for an interval of time. Afterward, the temperature of
the mold assembly is allowed to drop or is actively cooled. A
vacuum is applied within the tube, which now includes the blown
cuff, to release the tube and cuff from the mold assembly and the
tube and cuff are removed from the mold assembly.
[0033] For example, in one embodiment, a commercially available
extrusion of Dow Pellethane.RTM. 2363-90AE having an inner diameter
of 0.239.+-.0.005 inches (6.0706.+-.0.127 mm) and a wall thickness
of 0.015 mm.+-.0.007 mm may be blown to form a cuff 14 suitable for
use with a 7.5 mm internal diameter (ID) endotracheal tube. The
wall thickness may vary according to any specification for the
detection features, e.g., the cuff walls 55 may be thicker or
include certain shaped features. The extruded tube may be cooled to
room temperature and, when set, inserted into the mold assembly
automatically or by hand. Once loaded, the mold may be fitted into
a sleeve of a blow-molding machine. The sleeve may be heated, such
as by a series of ten electrical cartridges surrounding the sleeve,
thereby heating the mold. In this embodiment, the mold may be
heated to approximately 50.degree. C. prior to stretching or
blowing the extruded tube.
[0034] An air chuck locks on to one end of the extruded tube while
the other end of the extruded tube is sealed by a clamp to create
an airtight seal The extruded tube is stretched by pulling on both
ends of the tube and, while stretching, nitrogen or another
suitable gas or gas mixture is into the extruded tube via the air
chuck to pressurize the tube to between about 1 to about 3 bars. In
one embodiment, the balloon will form in the portion of the tube
situated within the mold when the tube expands under pressure to
make contact with the internal walls of the mold.
[0035] When the cuff is fully blown against the inner walls of the
mold, the mold may be heated (such as by heating the surrounding
sleeve) to between about 100.degree. C. to about 150.degree. C. and
this temperature may be maintained for between about 10 to about 30
seconds. After the application of heat, the mold may be cooled to
approximately 45.degree. C., such as by pumping refrigerated water
at approximately 13.degree. C. around the mold, to set the cuff. A
vacuum is applied to the molded extrusion and cuff, and the
extrusion and cuff are removed from the mold assembly. In
embodiments in which an antireflective coating is disposed on the
cuff, such coating may be applied to the finished cuff by any
suitable method, including dipping, spraying, coextrusion during
the extrusion process, sputter coating, etc. In other embodiments,
the antireflective material may be mixed directly into the cuff
material before the extrusion process.
[0036] While the disclosed embodiments may be susceptible to
various modifications and alternative forms, specific embodiments
have been shown by way of example in the drawings and have been
described in detail herein. However, it should be understood that
the disclosure is not intended to be limited to the particular
forms disclosed. Rather, the disclosure is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the disclosed embodiments as defined by the
following appended claims.
* * * * *